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Just listening to my very first Leak now and similarly very much enjoying the experience. After two years and two weeks finally gotten my Stereo 20 95% complete - just need to paint the can caps. All fine so far and no hiss/hum etc. Strange after all this time to suddenly be listening to it. Bit concerned with two of the EL34s as the getter is faint compared to the other pair. Sounds very good though, but imagine those Russian PIOs will need a few days to run in or whatever they do before it sounds at its best. Surprised how punchy/powerful the sound is, and this is running into a pair of 4-ohm Wharfedale Denton 85s! Couple pics below, but will start my own thread over the weekend.

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Leave those caps! They look great without matching. It is old ... it is still good ... does not have to look show-room new.

Best wishes from George

They’re brand new caps, and I have the paint already pre-mixed, as the transformer cowls all had to be repainted. Couldn’t resist getting the amp together to try her out today though, so they’ll be getting painted soon. Will stop hijacking Tony’s thread, but will explain further when I start my own thread on my restoration dramas :)
 
Just listening to my very first Leak now and similarly very much enjoying the experience. After two years and two weeks finally gotten my Stereo 20 95% complete - just need to paint the can caps. All fine so far and no hiss/hum etc. Strange after all this time to suddenly be listening to it. Bit concerned with two of the EL34s as the getter is faint compared to the other pair. Sounds very good though, but imagine those Russian PIOs will need a few days to run in or whatever they do before it sounds at its best.

Looks superb! I’d keep a very close eye indeed on those two EL84s, if they are as faint as the look in the pics the vacuum may be on the way out and failure imminent. As ever 6p14p-EVs are the answer unless you want to spend LOLprice.

It will get a good bit better as it wakes up. Despite my TL12 Plus having an issue they’ve gone from ‘good’ to ‘just stunning’ within the time I’ve been running them. I’m amazed by how big and dynamic a sound they can push out of LS3/5As!
 
Looks superb! I’d keep a very close eye indeed on those two EL84s, if they are as faint as the look in the pics the vacuum may be on the way out and failure imminent. As ever 6p14p-EVs are the answer unless you want to spend LOLprice.

It will get a good bit better as it wakes up. Despite my TL12 Plus having an issue they’ve gone from ‘good’ to ‘just stunning’ within the time I’ve been running them. I’m amazed by how big and dynamic sound they can push out of LS3/5As!


Ta. Over the moon with how good it’s sounding already. Really wasn’t expecting that powerful bass kick either, and that just with the stock value 32uF caps. They make my Wharfdale Denton 85s sound huge! Almost makes my Quad 606 sound anaemic... Amazing.

Think you’re right, and have just ordered a set of those 6p14p-EVs. £90 all in but worth it for piece of mind I guess. Not sure whether to risk still running it under close scrutiny until the new valves arrive now (which won’t be until mid-late May). Hard to leave it unused again after a very enjoyable evening of music, but I guess a few extra weeks wait won’t make much difference, just frustrating.

But anyway, what an amp!

Fingers crossed you get those Kemet 1uF caps tomorrow, and they solve your issue. RS usually delivery within 24 hours.
 
The Russian and eastern EU stuff often lands faster than you might expect. I used up my ‘stash’ of K40Y-9s doing the TL12 Plus so I ordered some more as spares from a couple of suppliers on eBay and they all landed far sooner than I expected, only about a week, and I didn’t get battered with any tax either! I like the idea of having at least one recap in hand for these amps even though the the K40Y-9s seem to last pretty much indefinitely from what I can tell. They will eventually run out and at that point the price will inevitably go up. Makes sense to have some in stock.

PS For others who haven’t seen them K40Y-9s are a Russian military paper in oil cap designed for extreme environments (space, submarines, tanks etc) and are a heavy solid aluminium casting sealed with glass. They are quite unlike any cap I’ve ever seen and would cost an absolute fortune if they had a boutique audiophile brand stamped on the case!
 
The rearmost pair of EL84s look well worn, the getter flash is getting pretty thin. Which may not mean anything...
 
@ John_73,
Sorry to thread creep but,
What value (wattage) resistors did you use for the 270Ω bypass R14 / R15?
Have you done any voltage measurements yet? Measuring across the 270Ωs will tell you a lot about the EL84s condition. As will measuring across the 100Ω Green resistor.
 
Whilst we are on John’s amp I love the layout and workmanship of the extra cap and resistor around R5, that is properly neat and way, way better than my untouched original grey one! If I ever add those to my earlier bronze S20 (it just has R5, nothing else) I’ll copy that technique!
 
Here's a better picture of that faint valve mentioned earlier, compared to the good one. Does it look like an impending Dead Parrot?

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All you can say is the one you mark ''bad'' has had a hard and or long life. It might live a good while longer or expire tomorrow...
Measure the voltage across each of your 270Ω Mills resistors, it should be 10 to 11 volts. That at least will give an indication if the EL84s are in spec or not.
 
All you can say is the one you mark ''bad'' has had a hard and or long life. It might live a good while longer or expire tomorrow...
Measure the voltage across each of your 270Ω Mills resistors, it should be 10 to 11 volts. That at least will give an indication if the EL84s are in spec or not.

Thanks very much, I'll do that today.

It was playing for just over a couple hours yesterday and I couldn't hear any hiss, hum or distortion from that channel, so I guess that's a good sign. I think from what my Uncle told me about the Stereo 20 way back, it did have a bit of a meltdown in the 90s (the usual issue of the cap closest to the 100R wire wound drying out, and causing issues with extra current draw until the issue was repaired). The wax that was left at the bottom of the mains transformer shows it was under duress for a while, though thankfully no damage was actually done to it, and I took it apart to have a good look etc. I'm guessing those two valves for a time were running much harder than normal compared to those two on the other side.
 
Have you got a nice long mains extension or similar? Might be worth having the ability to kill the power immediately from the listening seat if you hear anything odd or see any red-plating etc.
 
All you can say is the one you mark ''bad'' has had a hard and or long life. It might live a good while longer or expire tomorrow...
Measure the voltage across each of your 270Ω Mills resistors, it should be 10 to 11 volts. That at least will give an indication if the EL84s are in spec or not.

Exactly.
 
Have you got a nice long mains extension or similar? Might be worth having the ability to kill the power immediately from the listening seat if you hear anything odd or see any red-plating etc.

Yes fortunately very easy to kill the power quickly if need be. I'm not familiar with the failure modes of valves. Would there be some kind of warning like distorted reproduction or hum or something? Or would it be sudden and risk the newly installed components?
 
Apologies for a lack of knowledge here, but I assume I put the multimeter on DC, and have one probe placed either side of each 270R in turn?
 
The 270 R resistors normally have about 12 Volts across them which equates to 44mA. This results in 528mW or just over half a watt. Therefore a 1W resistor is fine. A bigger one will last forever. However in a fault situation it would be best if the resistor burnt out before anything else (expensive transformers) so 1W is better than 5 in this instance.
 
Here you go.
Negative lead on chassis earth / ground. Use the bolt thread. Put the ''bad'' EL84s in the side by the rectifier (GZ34) and the ''good'' ones in the side between the silver caps.
Meter on 20 volts DC range, then positive lead on 1, 2, 3, 4. in turn. You can compare results, 1 & 2 (bad) with 3 & 4 (good). 10 to 12 volts is 'normal'.

Now change the meter to 1000 volts DC and measure points 5 and 6. There should be about 15 or 16 volts difference.



Remember, do not run the amp without speakers or a dummy load.
 
Thanks very much for annotating the photo, that makes it perfectly clear. Much appreciated. Will hopefully get to measure that later this evening.
 


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